Various types of solar cells have been developed over the years. One type of solar cell is the donor-acceptor (DA) organic solar cell, which is formed using two different plastics or other polymers. In these types of solar cells, light absorption leads to the formation of an exciton (a bound electron-hole pair) that diffuses to a donor-acceptor heterojunction interface. This interface is formed at the contact between two organic semiconductors with different valence bands (VB) and conduction bands (CB).
The exciton dissociates at this interface into a hole and an electron. If an exciton is created in the donor material and reaches the donor/acceptor interface, the electron is transferred to the acceptor material, while the hole recedes in the donor material. Similarly, if an exciton is created in the acceptor material and reaches the donor/acceptor interface, the hole is transferred to the donor material, while the electron recedes in the acceptor material. The hole travels through the donor material to a first electrode, and the electron travels through the acceptor material to a second electrode. In this way, holes and electrons can be used to supply power to an external component coupled to the electrodes.